Space-Time Optical Systemsfor Encryption

of Ultrafast Optical Data

J.-H. ChungZ. ZhengD. E. LeairdProf. A. M. Weiner

Ultrafast Optics and Optical FiberCommunications Laboratory

Electrical and Computer Engineering &Center for Education and Research inInformation Assurance and Security

4/20/00Ultrafast Optics and Optical Fiber Communications Laboratory2

Ultrahigh-SpeedOptical Communications

l CAPACITY increased at over 4 dB per year.– Experiments with 1 Tb/s and higher.– Commercial systems with 400-Gb/s.

l ELECTRONIC ENCRYPTION has difficultiesabove ~ 10Gbit/s.

l Our research aims at OPTICAL ENCRYPTIONBOXES AT PHYSICAL LAYER for such highspeeds.

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Transmissioncapacity(though SMF)versus year

Progressin Speed

[A. R. Chraplyvy; Bell LabsTechnical Journal, Vol. 4, No.1, 1999]

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Optical Time-Division-Multiplexed(TDM) Transmission

l Resembles conventionalelectronic networks.

l Focus on packetprocessing includingHEADER RECOGNITIONand ENCRYPTIONof TDM OPTICAL DATAat 100 Gb/s and beyond.

ShortPulseGen

OpticalMod

Signal

OptMux

~20Gb/s100Gb/s~ 1Tb/s

Modified from [S.Kawanishi, NTT; IEEE Journal ofQuantum Electronics, Vol. 34, No. 11,Nov. 1998]

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Optical Encryptionat Physical Layer

ApplicationLayer

SONET/ATMLayer

Photonic transport /Network Layer

SONET

OpticAccess

LANVoice

VideoCATV

ATM

WDM

TDM

OpticalEncryption

Box

Modified from [D. Salameh et al.; Bell Labs Technical Journal, Vol. 3, No. 1, 1998]

100Gb/s Rate

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High-SpeedOptical Encryption Box

Adapted from [J.Ingle and S. McNown,DARPA/NSF Workshop on theRole of Optical Systems andDevices in Security and Anti-counterfeiting (Washington, D.C.,1996)]

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Subsystems for Ultrahigh-SpeedOptical Encryption

l Serial-to-parallel converter to allow header recognitionand packet processing at rates compatible with electronics

l Key generator arrayl Ultrahigh-speed optical XOR gate or array of high-speed

optoelectronic XOR gates for stream cipher (for example)l Parallel-to-serial converter to reform the ultrahigh-speed

TDM data stream

We are working on novel parallel optical/optoelectronicsubsystems to implement the serial-to-parallel conversion,parallel XOR gating, and parallel-to-serial conversionsubsystems.

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Approach ofSpace-Time Processing

lManipulates optical data in parallel to keep up with high speed stream.lPulse shaper: generate ultrafast test waveformslTime-to-space converter: Serial stream => Parallel data inputlSmart Pixel optoelectronic array: Digital logic operations like headerrecognitionlSpace-to-time converter: Parallel data output => Serial stream

Time-to-Space

Converter

Space-To-Time Converter

SpaceDomain

Processing[Serial-to-parallel] [Parallel processing

Using optoelectronicSmart Pixels]

[Parallel-to-serial]

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Direct Space-To-Time Pulse Shaper(Space-To-Time Converter)

DST pulseshaper

Input

1 1 0 0 1

Output

Modulatorcontrol

Scheme

Time (ps)-30 -20 -10 0 10 20 30

20 pixel3:1 duty cycle

10 pixel6:1 duty cycle

20 pulses at 530 GHzrepetition rate

[D.E. Leaird and A.M. Weiner;Optics. Letters Vol. 24, P.853-856, 1999]

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Direct Space-To-TimePulse Shaper Apparatus

m(x): PixelationPlane - fixed mask

100 fs pulsesat 850 nm from

Ti:S laserλ/4

‘Modulation’ Plane

Slit

PulseShaping

MaskGeneration

x2

x1

d1

d2

f

[D.E. Leaird and A.M. Weiner;Optics. Letters Vol. 24, P.853-856, 1999]

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Femtosecond Data Packets

Time (ps)-30 -20 -10 0 10 20 30

1 1 1 1 0 1 10 1 0 0 1 0 0 0 1 1 1 10

0 0 0 1 1 0 11 0 0 1 1 1 0 0 1 0 1 11

lTarget application ofDST.

lThe ‘state’ of eachtemporal pulse isdetermined by thetransmission at a uniquespatial location.

[D.E. Leaird and A.M. Weiner;Optics. Letters Vol. 24, P.853-856, 1999]

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Time-to-Space Converter

NLC: Nonlinear crystalG: GratingL: LensEs: Signal beamEp: Pump beamS: Spatial replica after a Fourier-transform lens

• Using a reference pulse, make Spatial replica of inputsignal pulses.

•We have demonstrated 500 times sensitivityimprovement, which is key for operation at realisticpower budgets in high-speed systems.

[A.M. Weiner and A.M. Kan’an;IEEE Journal of Selected Topics InQuantum Electronics, Vol. 4, No. 2,Mar/Apr. 1998]]

Modified form [P.C.Sun, Y.T.Mazurenko and Y. Fainman;Journal of the Optical Society ofAmerica A, Vol. 14, P. 1159, 1997]

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Optoelectric-VLSI Smart Pixel Array

l Hybrid CMOS/GaAs fromLucent foundry

l 200 Optical I/O’sl High-speed modulator array

functionality for ultrafastoptical packet generation

l AND gate array functionalityfor experiments on ultrafastoptical header recognition

l XOR gate array functionalityfor experiments on ultrafastoptical stream cipher

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Digital Logic Operationof Smart Pixel Array

l Processes the spatially-converted data in parallel,using an array of detectors

l The data would be XORed electronically with a storedkey, to implement a stream cipher.

l The processed data then drives an optoelectronicmodulator array inserted in a suitable space-to-timeconverter to get back to a serial ultrafast optical signal.

l Works out to frame rates of a few Gb/s to be able toachieve overall data rates exceeding 100 Gb/s.

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Other Approach to Encryption:Optical CDMA

l Encoding/decoding of ultrafast waveforms at the bitlevel

l Provide security at the physical layer– Keep unauthorized users without key from getting access to

the bitway.

l Can circumvent electronics bottlenecks and potentiallyimplement directly in the optical domain certainnetwork operations, such as addressing and security,which traditionally have been performed electronically

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Schematic ofUltrashort Pulse Optical CDMA

[Z. Zheng and A.M. Weiner,Conference for Optical FiberCommunication, Baltimore, Mar.2000]

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Decoding a Pulse

DECODEDPULSE

INCORRECTLYDECODED

PULSE

We have demonstratedcoding, transmission,decoding, and opticalcorrelation of femto-second pulses overmulti-kilometer fiberspans.Modified from [Z. Zheng, S. Shen, H.Sardesai, C.-C. Chang, J.H. Marsh, M.M.Karhkhanehchi, and A.M. Weiner, OpticsCommunications Vol. 167, P. 225, Aug. 1999]

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Conclusion

l Using space-time processing technique, wecan perform encryption operation on opticaldata at the physical layer, especially in thehigh-speed optical TDM transmission.

l Optical CDMA scheme can also encode anddecode optical data at the physical layer for thepurposes of addressing and security.